Construction of Guitars

Who invented the guitar? How does an electric guitar work? What is the difference between nylon and steel string guitars? What kind of woods are used? And other questions Tom has been asked about construction of guitars.

61. How does an electric guitar work?

There are different kinds of electric guitars, but the one most people think of as an electric guitar, Les Pauls, Strats, and the like, use a magnetic pick up, which is simply copper wire wound around a magnetic core. This creates a magnetic field which is disturbed by the vibration of the metal strings. This produces a weak current that is amplified to produce the sound.

62. What kind of woods are guitars made from?

Most acoustic guitars have either cedar or spruce tops. The top of the guitar is the most important part because that’s what creates the sound. Acoustic guitars mostly have spruce tops, whereas classical guitars generally have cedar tops. The opposite is also true. The most favored wood for the sides and backs of guitars is Brazilian rosewood, but it’s rare. Indian rosewood, mahogany, spruce and even black walnut are often used for sides and backs, and there are a lot of other woods that sound good too. One of the most popular woods for electric guitars is ash.

63. Who invented the guitar?

Guitar-like instruments have been around for thousands of years, but it’s generally acknowledged that the Spanish invented the guitarra and the vihuela in the late 15th century after they threw the Moors out.

64. What's the difference between nylon and steel strings?

Steel string guitars are more popular in North America than nylon because the popular music of the US and Canada generally uses the steel string. Classical and Latin American music tends to favor the nylon. Nylon string guitars have much lower tension strings and a much wider fingerboard than the steel string. But both guitars play the same notes and require similar technique.

65. How do 12-string guitars work?

Twelve-strings are simply six course guitars. A course is one of more strings tuned to the same pitch. What this means is, a twelve-string has all the same chord shapes in intervals as a six string. The first two courses on a twelve-string are in unison like a mandolin. But after that, the strings are in octaves. So if the fifth string is a G, just like the third string of a six-string guitar, then the sixth string is G an octave higher. The effect of all these high strings is a much fuller sound.

66. Do guitars come in different sizes?

Yes, they do. In the past two hundred years have grown quite a bit. In the mid 19th century Torres created a larger and louder classical guitar. Most of our classical guitars today are based on his ideas. In the early 20th century, Martin introduced the dreadnaught (named after a battleship). Jumbo bodies and big arch tops guitars were created in the 20th century. A lot of the smaller designs from the past are still available today. People of small stature may prefer these instruments, and some people just like the tone they produce. You can get a replica of a 19th century parlor guitar or a Martin 00 series and they’re wonderful sounding guitars. Though they’re smaller than one is used to seeing today, they’re not children’s guitars.

67. How long will a guitar last?

Guitars don’t go stale. A well-made guitar will last a very long time. There are guitars in museums from three hundred years ago. I myself have a guitar that was built in the 1820s and it’s still playable. There are a lot of really fine older guitars that are still quite playable and somewhat sought after. Martin guitars from the 1930s are thought well of in some circles, and they sound better now than they did in the 1930s. Cheaply made guitars will often fall apart; their necks will bend. And a lot of other things can go wrong with them over time. The theory is that an inexpensive guitar made in a factory made in Asia will have a life of about five years before it will become unplayable because the neck will have bent, the bridge will have pulled up and the top will have bellied out behind the bridge. A well-made guitar can be an investment. One fellow I know has a guitar his uncle bought for him when he was a child in the 1950s, and here in the 2000s, he’s still playing the same guitar. It’s his only guitar and has always been his only guitar. I guess he lucked out.

68. How have guitars changed over the years?

Since the six-string guitar emerged at the beginning of the 19th century, they have gotten larger. People started putting metal strings on them in the late 19th and early 20th centuries. Of course their shapes have changed a lot. Arch top guitars were very popular for awhile. They seem to have died out quite a bit. Arch top has a top and back more like a cello than the standard flat top guitar that we normally play today. Guitars have acquired, of course, electric pickups. Some have midi interfaces so you can play them with synthesizers. There are a variety of different pickup systems for acoustic electrics. Numbers of strings have changed some. There have been movements toward the seven-string guitar, and the ten-string guitar. There have also been five-string guitars, four-string guitars, twelve-string guitars. There are many styles and designs of guitar, and new ones are being tried and many discarded as time goes by.

69. Is there a reason the guitar is shaped the way it is or is it just style?

Yes there is a reason: the guitar is shaped the way it is because of the air flow inside the guitar. The two bouts, the upper and lower bouts, actually produce different frequencies in the tone of the guitar.

70. What effect does body size have on the sound of an acoustic guitar?

The size of an acoustic guitar's body affects the tone because of the volume of air inside and the area of the top of the guitar where the sound is produced. There's a big difference between a small bodied parlor guitar and a big jumbo body. Though larger guitars aren't necessarily louder than smaller guitars.

71. Why does the guitar have a hole on the top?

A guitar is nothing but a fancy air pump. The vibration of the top and back of the guitar working together cause the air to move in and out of the sound hole very quickly producing sound. The hole is where the sound comes out.